Field of the Invention
The present invention relates to a deformation analysis apparatus, and in particular to a deformation analysis apparatus that performs deformation analysis on a measurement target object.
Description of the Related Art
Hitherto, as deformation analysis apparatus that ascertain deformation states of a structural object, an apparatus is known that measures by employing a tape sensor using a strain gauge when performing two dimensional measurement on a measurement target object (see Japanese Patent Application Laid-Open (JP-A) No. H10-33506). A measurement system employing a piezoelectric film sheet is also known (see JP-A No. 2006-38710).
For 3D measurements of a measurement target object, a laser 3D deformation analysis apparatus, a micro CCD scope, ultrasound measurement apparatus, an X-ray measurement apparatus, and the like are also known (see JP-A No. 2010-66169). Apparatuses that employ strain gauges and CCD cameras are also known (see JP-A No. 2005-182529).
For two dimensional measurements of a measurement target object, tape sensors and piezoelectric film sheets are capable of measuring deformation of a measurement target object only in two dimensions due to the measurement range being two dimensional deformation. However, in reality many measurement target objects deform more than a little in three dimensions, with the issue that errors arise in measurements using tape sensors and piezoelectric film sheets. This is due to errors in curvature measurement when computing deformation using tape sensors and piezoelectric film sheets. Namely, this is because in measurements using elongated sensors such as tape sensors and piezoelectric film sheets, components due to twisting deformation are superimposed on measurement values of strain gauges and electromotive force of piezoelectric films when twisting deformation is imparted to the sensor at the same time as bending deformation. This gives rise to the issue that measurement target objects measurable using such sensors are limited. Such sensors employ circular plates of known curvature so that twisting deformation does not occur in order to associate strain and electromotive force with curvature.
In the method of JP-A No. 10-33506, in order to measure a measurement target object surface using tape sensors to measure changes in shape of a surface with high precision, a body supporter is employed for the purpose of placing the tape sensors in close contact with the surface. However, there is an issue that the obtained results are unable to sufficiently measure change in shape of the surface, since no consideration is given to changes due to extension of the surface. Explanation follows regarding FIG. 39A and FIG. 39B. A natural length state of a flexible body M is the deformed state as illustrated in FIG. 39A. However, when external force acts, the deformed state is as illustrated in FIG. 39B. In the state of FIG. 39A, the length of a sensor N is length LB from a fixed end G to a measurement point B. However, in FIG. 39B, due to the length of the sensor N being fixed, the shape measurement range of the flexible body M is a length as far as the vicinity of a measurement point A. In response to deformation of the flexible body M, the range the sensor N measures thus changes according to the deformation state. However, in the state of FIG. 39B, if LN, the length of the sensor N, is longer than the length LM of the flexible body M, all the deformation of the flexible body M in the states of FIG. 39A and FIG. 39B can be measured, however the extension length due to deformation of the flexible body M still has an influence on the measurement result of the sensor N.
Moreover, as apparatuses for the purpose of 3D measurement, measurements are performed using lasers, ultrasound, X-rays, and the like, and CCD cameras. However such apparatuses take a sighting of the measurement face of the measurement target object. Namely, visual data needs to be obtained. Thus there is the issue that measurement is difficult due to not being able to obtain visual data, for example, in cases where the measurement face is in contact with another object face, or cases in which the measurement target object is within another object. A specific example of a case in which the measurement face is in contact with another object face is deformation of a seatback or seat cushion face, and deformation of the face of the back and the face of the buttocks in a seated state of a person or dummy in a seat. A specific example of a case in which the measurement target object is inside another body is deformation of the spinal column and deformation of rib bones or the like of a dummy employed in a crash test. Moreover, there is the issue that the conditions of measurement are limited due to it being difficult to measure with such apparatuses in cases in which the external profile and volume of the sensors is large, and the measurement target object is tiny, and in cases in which the space to perform measurement is confined.